1. Field of the Invention
The present invention relates to safety razors having a detachable blade cartridge, and, more particularly, to a safety razor designed to improve the moving trace of the blade cartridge on the curved skin of the face, thus maintaining a uniform skin contact area and uniform skin contact pressure, with the hinge points of the blade cartridge of the razor provided at the handle of the razor at a position below the central axis of the cartridge so as to enlarge the swing angle of the cartridge, and allow the blades of the cartridge to effectively and cleanly shave the face without damaging or cutting the skin regardless of a variety of cutting resistances applied to the cartridge due to various hair densities and various curvatures of the face, the razor also having an elastic actuation unit used for smoothly and elastically rotating the blade cartridge around the head, and removing the cartridge from the head as desired.
2. Description of the Prior Art
Safety razors, with a guard to prevent the blade from cutting the skin, are designed such that a blade cartridge having multiple blades is movably and detachably attached to the head of a handle so as to smoothly swing around its hinged points according to the curvature of the user""s face. An example of such safety razors is referred to Japanese Patent Laid-open Publication No. Heisei. 3-52,319. This Japanese safety razor comprises two cartridge holding arms, which are hinged at opposite ends of the head of a handle so as to be rotatable in opposite directions around their hinged points. A spring-biased actuation button is set in the head of the handle at the middle portion between the two arms such that the button is elastically movable forward or backward. When the button is moved to the back, the two holding arms are closed. When the button is moved forward while compressing the spring, the two holding arms are open to allow an attachment or removal of a blade cartridge relative to the head of the handle. A pusher is provided between the two holding arms, and comes into pressure contact with the blade cartridge at its front end. The blade cartridge is thus rotatable around the hinge shafts of the two holding arms at a predetermined angle.
However, this safety razor is problematic in that the two holding arms may be undesirably or unconsciously opened to allow the cartridge to be removed from the razor since the holding arms in the closed position are supported only by the spring.
In an effort to overcome such problems, Japanese Patent Laid-open Publication No. Heisei. 11-156068 discloses a safety razor, which is designed to reinforce the spring force of the spring biasing the cartridge holding arms, thus almost completely preventing the holding arms from being undesirably or unconsciously opened. In order to accomplish the above object, this razor comprises two cartridge holding arms, which are hinged at opposite ends of the head of a handle so as to be rotatable in opposite directions around their hinged points. An actuation unit is set in the handle, and is used for actuating the two cartridge arms. A movable pusher is provided in the head of the razor at the central portion such that the pusher is movable forward and backward, with an elastic biasing member set between the movable pusher and the actuation unit. When a blade cartridge is firmly attached to the head of the razor, the cartridge pushes the pusher to the back while compressing the elastic biasing member. Therefore, due to the spring force of the compressed biasing member, the two cartridge holding arms are held in the closed position.
In the above razor, the blade cartridge is rotatable around the cartridge holding arms of the head. In addition, the attachment or removal of the blade cartridge relative to the head of the razor is accomplished by a forward and backward movement of the spring-biased pusher. Therefore, the swing angle of the blade cartridge relative to the head is undesirably limited. In addition, it is almost impossible for the blade cartridge to move precisely, and so the blades of the cartridge fail to effectively or cleanly shave the face, but may damage or cut the skin of the face while shaving. Another problem experienced in the above safety razor resides in that the two cartridge holding arms are operated in conjunction with the spring-biased pusher at the same time, thus creating mechanical friction and overloading the cooperation mechanism provided between the two holding arms and the pusher. The hinge points of the two cartridge holding arms are aligned with two projections formed at the front end of the pusher, and so it is almost impossible to smoothly or easily attach or remove a blade cartridge relative to the head of the razor when either the two cartridge holding arms or the pusher fails to desirably operate.
Each of the above-mentioned two Japanese safety razors uses a blade cartridge, which comprises one or more blades, a cap holding the blades, and a guard for preventing the blades from cutting the skin. In the above razors, the hinged points of the blade cartridge are positioned along the central axis of the cartridge. That is, in the case of a blade cartridge having double blades, the hinged points are positioned along an axis extending between the two blades in parallel to the two blades. Therefore, when the blade cartridge is rotated with reverse moment while shaving, the blades may cut the skin. In addition, the pressure of the blades is directly applied to the skin of the face while shaving, and so it is almost impossible for the blade cartridge to smoothly move on the skin while sensitively responding to any curvature of the skin or any blemishes on the skin. When the hinged points are set along the central axis of the guard of the cartridge so as to prevent an increase in the resistance acting on the blades of the cartridge according to the hair density while shaving, the swinging action of the cartridge is undesirably stopped in the case of an excessive increase in the pressure acting on the cartridge while shaving. In such a case, the blades of the cartridge damage or cut the skin.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a safety razor, which is structurally improved in the blade cartridge, the cartridge holder, and the head of the handle to allow the blade cartridge to move on the curved skin while being smoothly, sensitively and elastically rotated around the hinged points at an enlarged swing angle, and which is provided with separate elastic biasing members for respectively allowing the desired elastic swinging action of the blade cartridge relative to the head of the handle and allowing an easy attachment or removal of the blade cartridge relative to the head, and which is thus improved in its operational reliability and durability, and is almost free from damaging or cutting the skin while shaving.
Another object of the present invention is to provide a safety razor, of which the hinged points of the blade cartridge are positioned at the front end of the head of the handle at a position below the central axis of the cartridge, thus allowing the cartridge to be rotatable backward around the hinged points at an enlarged swing angle when a user unconsciously and excessively presses the cartridge against the skin while shaving, and which thus safely and cleanly shaves the face while maintaining a uniform skin contact area and uniform skin contact pressure without damaging or cutting the skin, regardless of a variety of cutting resistances applied to the cartridge due to various hair densities and various curvatures of the face.
In order to accomplish the above object, the present invention provides a safety razor, comprising a blade cartridge removably and rotatably attached to the head of a handle, wherein the blade cartridge is attached to the head at the hinged points formed at the front end of the head at a position below the central axis of the cartridge, thus allowing the rotatable cartridge to create a single directional moment during a rotating action of the cartridge around the hinge points and allowing a restoring moment of the cartridge to be applied to only a cartridge holder of the handle, and preventing the blade of the cartridge from forming any pressure capable of damaging or cutting the skin while shaving. In the safety razor, the cartridge is rotatable backward around the hinged points at an enlarged swing angle when a user unconsciously and excessively presses the cartridge against the skin while shaving, thus safely and cleanly shaving the face while maintaining a uniform skin contact area and uniform skin contact pressure without damaging or cutting the skin.
In the preferred embodiment, the safety razor comprises a handle having a head provided with a mounting depression, a center channel axially extending from the depression to the front edge of the head, and a knob seat opening formed at the upper surface of the head; an elastic actuation unit seated in the mounting depression of the head and consisting of: a base block seated in the mounting depression of the head and having an axial bore, with a first pusher movably seated in the axial bore while being normally biased forward by a first biasing member; a second pusher axially and movably seated on the base block, with a second biasing member normally biasing the second pusher to the back relative to the base block; and an actuation knob seated on the knob seat opening of the head, and elastically moving the second pusher forward or backward in accordance with an operation of a user; a cartridge holder rotatably attached to the front end of the head, the cartridge holder being provided with a cam surface for being normally biased by the first pusher so as to elastically return to its stop position, the cartridge holder also having a plurality of cartridge locking pieces; and a blade cartridge having a projection formed on its lower surface at a middle portion, and removably attached to the cartridge locking pieces of the cartridge holder such that the front end of the second pusher comes into contact with the projection.